The present invention relates to a general purpose combined harvester and thresher (hereinafter, named xe2x80x9ca general purpose combinexe2x80x9d or simply xe2x80x9ca combinexe2x80x9d) having auger type threshing rotors oriented perpendicularly to its travelling direction.
It is popular that a conventional general purpose combine comprises longitudinally oriented threshing rotors with screw vanes on their peripheral surfaces as augers provided in its thresh unit, wherein grain rods, which have been reaped by its reaping header forwardly projecting from its driving machine, are conveyed backward and fed into the thresh unit, so as to be threshed by the rotating rotors. Straws as the threshed grain rods are spread from the rear of the combine onto the field. Grains and chips of broken grain rods and dust are dropped through a screen into a separate unit disposed below the thresh unit. The separated chips of waste straw and dust are discharged from the rear of the combine, and the separated clean grains are gathered in a grain tank disposed on a side of the combine. When the grain tank is filled up, the grains can be discharged from the grain tank through an unloading tube disposed above the grain tank into a bed of a truck or the like. The unloading tube can be swivelled and lifted on the combine.
The grain rods which have been cut and separated from their roots by the header are conveyed backward through the feeder to the foremost end of the threshing rotor in the thresh unit. The rotor has been provided at its front end with a pickup vane for introducing the reaped grain rods deep into the thresh unit. However, the direction of introduced grain rods is substantially perpendicular to the rotational axis of the pickup vane, while the grain rods are to be conveyed in parallel to the axis of the rotor through the thresh unit. Therefore, the inlet of the thresh unit is hard to introduce the reaped grain rods so as to be often clogged with them.
Also, the grain rods with the lengths as they have been reaped are threshed insufficiently in the thresh unit.
Front and rear threshing rotors are provided with respective screens covering their lower portions so as to define the space between the front rotor and screen as a first threshing chamber, and the space between the rear rotor and screen as a second chamber. The grain rods can be transferred from the first threshing chamber to the second threshing chamber only through a pass formed between the laterally overlapping portions of the front and rear screens, so that each of the screens is insufficiently used, thereby causing another reason for the low efficiency of the thresh unit.
The distance which the thresh unit can provide for conveyance of grain rods to be threshed is restricted correspondingly to the lengths of rotors, thereby causing remains of unthreshed grain rods in significant number.
Also, if the thresh unit is fed with significantly increased grain rods from the reaping header, the layer of grain rods conveyed on the screen becomes so thick that only the grain rods abutting against the screen are threshed while those being close to the rotor are left unthreshed.
The problem of unthreshed grain rods caused by the large amount of reaped grain rods cannot be solved by an increase in the number of rotors for increasing the distance in conveyance of the grain rods to be threshed, which merely increases the power requirements for threshing, or rather causes, if the grain rods cannot be transferred between the rotors smoothly, the portion between the rotors clogged with the grain rods, and complicates the maintenance of rotors.
Furthermore, the disposal of plural rotors requires the thresh unit occupy such a large space as to restrict the volume of the grain tank.
The problem associated with the separate unit is that tailings as mixture of grains and twings generated therefrom are insufficiently treated for separating clean grains, thereby causing the loss of grains and reducing the quality of clean grains as products.
Also, conventionally, the tailings are returned onto the midway portion of a grain-flow pan of a shaking separator, so that the tailings to be separated are unevenly distributed on the pan, thereby reducing the efficiency of separation.
The problem associated with the arrangement of the reaping header, the thresh unit, the separate unit and the grain tank on the combine body is that the conventional combine is ill balanced in its lateral direction because the threshing rotor or rotors are longitudinally oriented at some length and the grain tank is disposed on either left or right side of the rotor or rotors. More specifically, at the beginning of work, the combine is more weighted at its one left or right side where the thresh and separate units are disposed than the other right or left side where the grain tank are disposed because the grain tank is empty. The centroid of the combine gradually moves to the grain tank side as the grains are collected step by step in the grain tank during the progress of work. Finally, when the grain tank becomes full of grains, the grain tank side of the combine becomes more weighted than the thresh and separate units side thereof. Thus, the position of centroid is different in the lateral direction between at the beginning of work and after the progress of work, thereby confusing an operator""s feeling. What is worse, the combine, when the field is soft, is leaned laterally because of its lateral ill balance, so that the cutting level of reaped grain rods is different between the left and right halves of the combine.
The horizontal unloading tube for discharging grains from the grain tank is disposed above the grain tank, thereby complicating the mechanism for conveying grains from a grain elevator disposed under the grain tank to the horizontal unloading tube. Also, the horizontal unloading tube must be pivotally supported so strongly, thereby increasing the weight of the combine.
A general purpose combine of the present invention comprises a plurality of (particularly, two) auger type threshing rotors juxtaposed before and behind in its thresh unit, so that the reaped grain rods introduced into the thresh unit are successively threshed by the rotors, thereby solving the problem of leaving grain rods unthreshed.
Also, the rotary axis of at least one threshing rotor (especially, the axes of the two rotors) is oriented in the travelling direction of the combine, that is, perpendicularly to the direction of grain rods fed to the thresh unit, so that the grain rods introduced into the thresh unit are directly pressed against a screw vane provided on the peripheral surface of the first rotor, thereby improving the introduction of reaped grain rods into the thresh unit and reducing the longitudinal length of the combine. Furthermore, this construction enables the drive shaft of the rotor to be parallel to the drive shafts of augers disposed in a separate unit. Thus, bevel gears for reorientation of driving force are not required and the power transmission mechanisms for driving the shafts, which come to be collected on one side of the combine, are simplified, thereby saving costs.
A substantially rectangular slide framework is laterally slidably disposed in the thresh unit. The threshing rotor is journalled in the slide framework, so that the rotor together with the slide framework can be pulled out from the combine, thereby easing the maintenance and attachment of the rotor.
In the case of the thresh unit provided with two rotors, the rotational directions of the two rotors are made opposite to each other so that a layer of grain rods are reversed when they are transferred, whereby grain rods contacting one of the rotors are reversed so as to be pressed against the screen corresponding to the other rotor. Due to this, the combine is prevented from remaining of unthreshed grain rods however increased the grain rods to be threshed may be.
Furthermore, the front rotor is made outer diametrically larger than the rear rotor, so that they are allotted different functions. More specifically, the front rotor mainly threshes a lot of reaped grain rods introduced into the thresh unit so as to separate grains therefrom, and the rear rotor mainly conveys waste straws and secondarily separates remaining grains from the grain rods transferred from the front rotor, thereby saving consumption of driving power and lightening and compacting the thresh unit.
Tooth bars for cutting the grain rods introduced into the thresh unit are provided on a part of outer peripheral surface of the foremost threshing rotor which faces a feeder housing, thereby enhancing the efficiency of threshing.
Also, the pitch of the screw vane provided on the part of outer peripheral surface of the foremost rotor facing the feeder housing is made substantially as large as the width of the rear end of feeder housing, so that the grain rods from the feeder housing can be transferred from the part to the other part of the foremost rotor by its one rotation, whereby the part facing the feeder housing is prevented from being clogged with the introduced grain rods.
For transferring grain rods from a first threshing chamber underneath the front rotor to a second threshing chamber underneath the rear rotor, the rear rotor is rotated faster than the front rotor, so that the speed of grain rods conveyed by the rear rotor is higher than that by the front rotor, thereby reducing the thickness of layer of grain rods. As a result, sticking of grain rods in the screens, which causes some loss of grains, and jamming of grain rods between the rotors during the transferring thereof are prevented.
A terminal end of a tailing return conveyor extended from a tailing auger of the shaking separator is disposed so as to be connected to the head end of first threshing chamber, so that tailings from the tailing auger are threshed again by the first rotor so as to separate the grains from their twings, thereby enhancing the quality of clean grains as products.
Alternatively, the terminal end of tailing return conveyor extended from the tailing auger may be disposed so as to communicate with a laterally opposite space to the feeder housing in the thresh unit just above the upper surface of a grain-flow pan of the shaking separator, so that things to be separated are evenly spread on the whole of grain-flow pan, thereby enhancing the separation efficiency.
The grain tank is disposed above the thresh unit so that the grain tank can be laterally as wide as the combine body, thereby allowing the combine to be laterally evenly weighted however collected grains may be in the grain tank. Also, a bottom surface of the grain tank is disposed between the front and rear rotors so as not to move the weight point in the longitudinal direction even if the amount of grains in the grain tank is varied, thereby preventing the combine from unbalance.
Additionally, an unloading tube is disposed on either left or right side of the grain tank with its upstream end connected to a grain discharge conveyor disposed in the grain tank and with its terminal end forwardly projecting so as to reduce the transferring distance between the grain discharge conveyor and the unloading tube, thereby simplifying their driving and conveying mechanism and reducing the vertical length. Regarding the power transmission system, an engine is disposed behind the thresh unit so as to enhance the availability of a space below the driver""s unit. The resulting engine can be disposed in substantially lateral middle of the rear portion of combine so as to enhance the lateral weight balance of the combine. Also, the rear-mounted engine is disposed oppositely to the front-mounted reaping header, thereby enhancing the longitudinal weight balance of the combine.
A transmission casing is also disposed below the rear-mounted engine, so as to enhance the longitudinal weight balance of the combine and reduce the power transmission distance between the engine and the transmission casing.
On one left or right side of the combine where an output shaft of the engine projects laterally outwardly are disposed all power transmission mechanisms associated with the transmission casing, the rotors in the thresh unit, an air fan and the like in the separate unit, a cutter bar and a feeding conveyor in the reaping header, and various conveyors or augers, thereby being simplified in the power transmission among them without bevel gears and easing their maintenance.